Infinite towers of 2d symmetry algebras from Carrollian limit of 3d CFT

Abstract: We consider the Carrollian limit of OPE blocks of scalar primaries, spin-1 currents and the stress tensor in 3-dimensional conformal field theory (CFT$3$). We demonstrate that these OPE blocks decompose into OPE blocks of towers of $\mathfrak{sl}(2,\mathbb{C})$ modes labeled by negative integer dimensions. We present two applications of this construction. We first show that the current-scalar-scalar and stress tensor-scalar-scalar OPE blocks in CFT$_3$ reduce to $\mathfrak{sl}(2,\mathbb{C})$ OPE blocks from which towers of conformally soft photon and graviton theorems can be derived. We then show that the CFT$_3$ OPE blocks of, respectively, current and stress tensor components dual to positive helicity gluons and gravitons in AdS$_4$ become $\mathfrak{sl}(2,\mathbb{C})$ blocks of conformally soft gluons and gravitons which imply the $S$ and $w{1 + \infty}$ algebras of celestial CFT.